With rapid development of communications technologies, an interference cancellation (IC, Interference Cancellation) technology is introduced to improve an uplink data transmission rate. This technology reconstructs a received signal according to an estimate value of a user and is used to cancel a signal that interferes with a user, so as to improve a demodulated signal-to-interference-plus-noise ratio, thereby improving performance of a target user. The interference cancellation technology reduces uplink interference to obtain performance improvement by cancelling Dedicated Physical Data Channel (DPDCH, Dedicated Physical Data Channel) data, Dedicated Physical Control Channel (DPCCH, Dedicated Physical Control Channel) data, Enhanced Dedicated Physical Control Channel (EDPCCH) data, and Enhanced Dedicated Physical Data Channel (EDPDCH) data of each user in baseband data. Reconstruction is one of important steps of interference cancellation, and the quality of reconstruction directly determines cancellation efficiency of interference cancellation and system performance. One of important steps of baseband data reconstruction, however, is to add fading to a signal. Generally, a fading factor obtained by channel estimation is used during the adding of fading and is not an actual fading factor. For a process of baseband data reconstruction that is a process of simulating signal transmission, an actual fading factor is needed. A fading factor obtained by actual estimation, however, is affected by root raised cosine filters at a transmit end and a receive end, and is a result of superposing fading factors of all valid paths and not the actual fading factor.
For example, it is assumed that a channel fading factor is hl is an actual fading factor of each valid path, while a fading factor h′l obtained by actual estimation is a result of superposing fading factors of all valid paths because the fading factor h′l is affected by a root raised cosine filter at a receive end, that is, h′l obtained by estimation is as follows:
                                          h            l            ′                    =                                    ∑                              q                =                0                                            L                -                1                                      ⁢                                          h                q                            ⁢                                                R                  p                                ⁡                                  (                                                            τ                      l                                        -                                          τ                      q                                                        )                                                                    ,                  l          =          0                ,        1        ,        …        ⁢                                  ,                  L          -          1                                    (        1.        )            
During data reconstruction for IC, a process of data passing through a channel is simulated before data is received, and an impact of the channel on the data is simulated by using an estimated fading factor, and then the data is obtained after being processed twice by a root raised cosine filter (or once by a raised cosine filter). What is obtained through the channel estimation is a channel fading factor that includes an impact of a filter, that is, convolutions of the actual fading factor and Rp. When channel data is reconstructed for interference cancellation, a fading factor obtained by the channel estimation is used.
During research and practice of the prior art, the inventor of the present invention finds that, in an existing implementation manner, a fading factor obtained by channel estimation is not an actual channel fading factor, and reconstructed data largely deviates from data actually sent on a channel, thereby affecting a gain of interference cancellation and reducing efficiency of the cancellation.